Silicon has been used frequently for the manufacture of cantilevers adapted for instrumentations such as scanning probe and atomic force microscope. A cantilever can not only act as an arm providing a tip at its proximate end for applications, such as lithography and surface topography scanning, but can also provide a sensing mechanism to detect the distance between the substrate surface and the cantilever itself. See, for example, M. Tortonese et al., Appl. Phys. Lett. 62 (1993), pp. 834-836; U.S. Pat. No. 5,595,942 to T. Albrecht et al. More recently, piezoresistors have been incorporated into such silicon-based device. See, for example, R. Jumpertz, et al., In Proceedings, European Solid-State Device Research Conference (ESSDRC), pp. 680-683 (1997); F. Goericke et al., Sensors and Actuators A143 (2008), pp. 181-190; A. Gaitas, “Novel single cell disease markers with a hybrid AFM scanning piezo-thermal probe.” NIH grant 1R43GM084520-01, 15 May 2008.
One significant drawback of using silicon as a base material for the cantilever is the electrical charging of the probe and cantilever, and a lack of control of the electrostatic fields in the device, because silicon is an electrical conductor. Particularly, when the applications involve biological materials, either to sense these materials or to deposit these materials onto a substrate using lithography, the presence of an uncontrolled electrical field and other electrical charging mechanisms can adversely impact the applications.
Additionally, the commonly available piezoresistor utilizes lightly-doped silicon or intrinsic silicon often to maximize the piezo response. However, it is also generally known in the art that while the lightly-doped silicon design can provide a large piezo response, it can suffer a drawback of needing for temperature compensation, which is often difficult. See, for example, Y. Kanda, “IEEE Trans. Elec. Dev. ED-29, pp. 64-70 (1982).
Thus, there exists a need to provide a better height-sensing mechanism for the design of the cantilever.